GERMAN GLASS SECRETS.

Taranaki Daily News, 30 March 1916, Page 8

GERMAN GLASS SECRETS.

I THE MYSTERY OF JENA. , ENGLISH EXPERIMENTS. Already we are well on the way towards solving the secrets of the manufacture of Jena glass. Germany has practically monopolised the manufacture of certain kinds of glass possessing very remarkable qualities, and when the German supplies were cut off many important industries in Great Britain were .so seriously affected that our men of science were induced to undertake special investigations. All- the glass used in miners' safety tamps, for instance, was of German make, this glass possessing remarkable toughness and non-liability to cracking by heat and blows. As the result of investigations carried on at the Leeds University we are now making this glass. . SOLVING THE SECRETS. A special committee has boon working in London with the object of solving the secrets of manufacture of peculiar glass. The curious fact was that although chemical analysis gave the exact constituents, when the materials were mixed quite different glasses were formed, but now many of the actual qualities are being produced. Few people are* aware of the remarkable kinds of glass which made today. While the making of glass is carried on in all countries, in every ease the best optical lenses are made from that special kind called Jena glass. It is not at all an easy matter to provide /a lens which will transmit pure white ■light. Sir Isaac Newton thought it would he impossible to make such a lens; but Pollard made one by combining a piece of flint-glass and a piece of crown glass. * The remedy was not perfect, but it was only one possible Until Jena glass was discovered.

The first experiments to form a new glass for optical purposes were made by an English clergyman, the Rev. Vernon Hnreourt, in 1884, the investigations being carried on for 25 years. All'sorts' of experiments were made by allowing different glasses and introducing new ingredients. ■ About thirty years ago the Prussian Government provided Professpr Ernest Abbe and Dr. Otto Schott with resources to make investigations in (lie science and art of glass-making. The investigators began theii experiments at the town of .Tena. and as the result of many long and-costly experiments they produced some very extraordinary glasseshundreds of kinds. The main discovery, so far as photographers are concerned, was that of & glass which was almost perfectly transparent. At. present researches are being made to make a peculiar glass which will transmit only one color. COOLED FOR A .MONTH. One of the most noteworthy discoveries. at .Tena has been that of a glass which is utilised in making microscopic lenses. By these lenses it.is possible to photograph particles otbevwise invisible to the most powerful microscope. By the aid of this remarkable glass an object measuring only I.T-'i-'.flOO.OOOtli part of an inch in length may be brought to view indirectly. The infinitcsimally small size of such an object is beyond the powers of imagination. Some of the .Tena glass is annealed by heating, and is then slowly cooled for a month. The result is a glass which never alters its dimensions at ordinary temperatures. Another glass will resist the -action of hot. corrosive liquids. Still another kind of glass provide- a light of a peculiar kind, very useful In treating certain skin diseases. The rays from this glass cause severe irritation to the eyes and skin, but very quickly destroy disease germs, acting much the same as radium Glasses are now made which nrc nuite free from brittleness and corrodiabilily, find yet of a strength which is practically equal to tlm( of a metal